To interconnect an electric power generated at a power generation facility that uses a natural energy, for example, solar power generation and wind power generation, to an electric power system, a power conversion device is used. The power conversion device converts a voltage and a frequency into those of the electric power in the electric power system. The power conversion device includes a plurality of power conversion devices that perform power conversion between DC power and AC power, and the power conversion device is configured to include an insulation transformer and a power convertor such as a DC/DC converter and an inverter.
Generally, for example, in the case of a solar PCS for large-scale, a direct current from the solar power generation facility serves as an input to output a three-phase power of about 400 V. A high-voltage insulation transformer is used for a step-up output from the solar PCS to a high-voltage system (for example, 6.6 kV and 22 kV), and the high-voltage insulation transformer is forced to be driven with a low frequency of several tens of Hz identical to the frequency of the system, thus increasing in size. To achieve an outdoor installation of a PCS for large capacity, it is necessary to house the solar PCS inside a container or to adapt the solar PCS itself for outdoor on-board use, thus upsizing the facility.
While further loss reduction is ensured by shortening lengths of a DC wiring and a low-voltage AC wiring, it is difficult to dispose the solar PCS and an interconnection transformer immediately close to a solar panel in view of influence of a shade on the solar panel because of the large volume and weight of the solar PCS for outdoor use and the interconnection transformer as described above. Then, the solar PCS and the interconnection transformer have been generally disposed away from the solar panel.
PTL 1 has been known as a case where a power conversion device is disposed in association with a transformer board when configuring the power conversion device on board.
PTL 1 discloses that the power conversion device “includes: an input transformer 1 that includes a plurality of secondary windings; a transformer board 10 that houses this input transformer 1; a three-phase inverter that is connected to the secondary winding in a one-to-one basis and has respective phases in Y-connection, the phases each including a plurality of unit inverters 2 connected in series, the unit inverters each outputting a single-phase AC voltage in a desired frequency; and a converter board 20 that houses the unit inverters 2 constituting the three-phase inverter. The converter boards 20 includes a plurality of support pillars 22 made of insulators, and a plurality of metallic shelf boards 23 that fasten adjacent support pillars one another among this plurality of support pillars 22 in a lateral direction. The respective unit inverters 2 are placed and secured to the shelf boards 23.”